In current Third Generation Partnership Project 3GPP standards for mobile telecommunications such as Universal Mobile Telecommunications System UMTS, as shown in FIG. 1 when a radio network controller RNC requests a base station (Node B in UMTS terminology) to reconfigure its radio channel (bearer) to any particular mobile station (User Equipment in UMTS terminology, UE), the base station (Node B) will effect the reconfiguration only after it receives a Radio Link Reconfiguration Prepare message including configuration parameters as to the new uplink and downlink radio channels to be used, responds with a Radio Link Reconfiguration Ready message and then receives Radio Link Reconfiguration Commit message. The configuration parameters, i.e. which other new channels are to be used, are specified in the Radio Link Reconfiguration Prepare message. The radio link is, of course, synchronous, requiring both base station and mobile station to transmit and receive at expected times.
Importantly, as shown in FIG. 1, receipt of the Radio Link Reconfiguration Ready message by the base station results in the new radio data channels being allocated by the base station although not used until later. These significant resources are thus unused for a considerable time.
As also shown in FIG. 1, a Radio Bearer Reconfiguration message is then sent from the radio network controller RNC to the mobile station UE. Once reconfiguration is complete, a Radio Bearer Configuration Complete message is returned to the radio network controller RNC. Both the mobile station (UE) and base station (Node B) then start transmission with new channel configuration at a specified activation time denoted by a connection frame number CFN as part of the Radio Bearer Reconfiguration message.
Once the radio network controller RNC and a base station (Node B) making up the UMTS terrestrial radio access network UTRAN have performed these steps of instructing synchronous radio link reconfiguration, downlink transmission starts but both the mobile station (UE) and UMTS terrestrial radio access network UTRAN may need to re-run the so-called inner loop power control procedure described in the 3GPP UMTS standards due to the new radio channel configuration. This is to ensure that before user data is transmitted, the inner loop power control, which compensates for fluctuations due to mobile station movement and consequential fading, is properly set up and functioning. The time period required for inner loop power control can be up to 7 frames (70 ms). This time period is denoted Power Control Preamble (PCP) length, and is indicated to the mobile station in the Radio Bearer Reconfiguration message sent from the radio network controller RNC. As shown in FIG. 1, whilst the inner loop power control is running (in the PCP length period) no user data is transmitted uplink but the channel designated for transmission of user data uplink is reserved—i.e., allocated but not used. This means that the channels are committed by the base station (Node B) for at least the duration of the PCP length period doing nothing (i.e., not communicating user data), which is a waste of scarce radio resources.
In this text, uplink means from the mobile station to the base station, and downlink means from the base station to the mobile station.